if (typeof array !== 'undefined' && array.length === 0) {
// the array is defined and has no elements
}
if (typeof image_array !== 'undefined' && image_array.length > 0) {
// the array is defined and has at least one element
}
if (array === undefined || array.length == 0) {
// array empty or does not exist
}
if (array && !array.length) {
// array is defined but has no element
}
if (Array.isArray(array) && array.length) {
// array exists and is not empty
}